Electric gaseous discharge device



Jan. 15, 1935. A. CLAUDE 1 1,987,845

ELECTRIC GASEOUS DISCHARGE DEVICE Filed 001. 22, 1951 2 Shets-Sheet 1 Fig.1,

I 1' I l X 11 1 Y 2 3 l/llllE/LT0fi ATTUR/VEY Ja11. 15, 1935. A. CLAUDE 1,987,845

ELECTRIC GASEOUS DISCHARGE DEVICE Filed Oct. 22,1931 1 2 Sheets-Sheet 2 Fig.2

Patented Jan. 15, 1935 I UNITED 's'mnzs PATENT OFFICE Andr Claude, Nanterre, France Application October 22, 1931, Serial No. 570,451 In France November 5, 1930 14 Claims. 176-122) Lighting devices, in which the light is produced tube installations by reason not only of the inby an electric discharge in a rarefied gaseous atcreasing use of the light emitted by rare gases mosphere containing at least one rare gas, comas decoration and for advertising purposes but prise an electric circuit and a discharge apparatus also by reason of the uses anticipated by the epformed by a chamber enclosing on the one hand plicant for aeronautical and nautical beacons but 5 a gaseous mass and on the other hand the elecfurther for the lighting purposes themselves. trodes which traverse the walls of the said cham- The applicant has endeavoured to accomplish her and are connected to the current circuit. these purposes by utilizing the discharge on In these devices the difference in potential apthe arc principle, but entirely new difiiculties plied to the electrodes of the discharge apparatus have been faced which at first appear to be in- 10 and necessary to its working is divided into an surmountable. anodic drop of potential, a drop of potential along It is known that the transition from the lumithe positive column and a cathodic drop of potennescent principle to the arc principle is charactertial. ized more especially by a considerable increase in In the present arrangements of this type, the the intensity of the current carried by the disl5 pressure of the gaseous mass in the discharge charge. It is known however that the life of luapparatus is of several millimeters of mercury minescent tubes is a factor of the intensity and and in certain apparatus it is even of the order that Georges Claude (U. S. Patent No. 1,125,476) of a centimeter, and the intensity of the current has only been able to obtain luminescent tubes is or the order of several tens of milliamperes and which can function for any length of time which 20 at the maximum of the order of several hundreds is suitable to industrial needs, by the aid of elecof milliamperes. The anodic drop is slight being trodes, the surface of which is greater than 1.5 only of a few volts, but on the other hand the square decimeters per ampere. It will therefore cathodic drop which varies with the nature of be feared that increasing the current fed on the the cathode is always of a high value reaching arc principle will only be conducive to very short 25 several hundred volts and scarcely ever being less duration in spite of the use of electrodes having than about 60 volts. very large surfaces.

The electric energy absorbed by these falls in Further as the intensity of the current is very potential constitutes a loss from the point of view much increased the emission zone of the discharge of luminous efi'iciency.- from the cathode is reduced to a very small por- Since the fall in potential along the positive tion of the surface of the same. This portion is column is proportional to the length of this 001- called the cathodic spot, and at this spot conumn, the efiiciency can be improved by making siderable spattering of particles and release of the luminous column as long as possible but this vapour from the material forming the cathode results in a high feed voltage which generally takes place. amounts to several thousand volts. Although generally speaking, the cathodic spot These high voltages are only obtained in pracis displaced about the cathode its dimensions are tice with electric generators of alternating curso small that no increase of the surface of the rent and the electrodes of the discharge devices cathode according to the method used by Georges which then alternately act as anode and cathode Claude on the luminescent principle would pre are identical. vent the rapid disintegration of the cathode.

For convenience in expression, the electric dis- At the same time, the following fact observed charge apparatus having the general characterby the applicant with regard to the anode would istics stated above will be hereafter designated also lead to the fear of restriction of useful life under the name of discharge apparatus funcof the device functioninginthese conditions. tioning on the luminescent principle or more The applicant has observed in fact that if for simply luminescent tubes or apparatus. example a metallic foil in the form of a cylinder It is extremely desirable for reasons of convenis used at the anode, it is found that if there is ience and security for the apparatus to be fed a high enough ratio between the length of the under low voltage more particularly at the usual cylinder and its diameter, only a more or less 50 domestic distribution voltages, for example at large band on the end of the cylinder is affected 110 or 220 volts and with continuous or alternatby the discharge and it is especially on this band ing current. At the same time, it is absolutely and more particularly on the edges of the same desirable to obtain luminous efliciencies which are that the metal acts and vapourizes.

5 at least equal to those of the present luminescent Therefore not only is the current much more I intense on the arc principle, but only a very small part of the cathode and even a small part be increased twenty times.

of the anode (which will hereafter be termed anodic zone") serve for emission. It follows that the density of the current per square decimeter surface of the electrode, which is the chief factor in the long life of luminescent tubes of rare gases, become enormous in the operation of the arc. When it is considered that the life of a rare gas electric discharge apparatus functioning on the luminescent principle decreases very rapidly when the intensity of the current increases one might think that the arc principle will be normally useless for these apparatus and that these will deteriorate very quickly.

It is very important to remark here that the apparatus functioning under low tension cannot have any considerable length or consequently be of any considerable volume. The reserve of gas that they contain is therefore generally comparatively small with regard to that of luminescent tubes this again increasing the difliculties.

It seems therefore that there is only one means for overcoming these great diillculties, that is to increase the charging pressure of the luminescent gas, as it is known that the higher this pressure, the lower is the volatilization of the electrodes, everything else remaining unchanged. I

However, in contrast to all that one might suppose, and to what has up to the present time been indicated, applicant has found that it was possible to obtain a satisfactory life not only with the low pressures indicated by Georges Claude for luminescent tubes that is to say with pressures of the order of millimeters of mercury, but with still lower pressures which in certain cases may be of the order of some hundredths of a millimeter of mercury.

Evidently one of the essential facts in the origin of the great difference between the luminescent principle and the arc principle is that the volatilization which occurs at the electrodes and the subsequent condensation of the volatized particles of the material of which the electrodes are made (this being the essential reason for the absorption of the gases), are due not only to the density of the current, but also to the quantity of energy expended at the electrodes that is to say to the number of watts per square decimeter of the electrodes (this number being the product of the density of the current by the fall in potential at the electrodes). When we pass from the luminescent principle to the arc principle the cathodic drop in potential suddenly falls to a few volts and it can, therefore be concluded that densities of current higher than on the luminescent principle can be accepted by the cathode. This reasoning howeved, does not appear sufficient to explain a state of affairs which truly result in a most surprising effect.

Taking for example the use of potassium electrodes in neon gas, the cathodic drop falls from about volts on the luminescent principle to 2 to 5 on the arc principle, that is to say about a twentieth of its value. The density of the current possible on the arc principle could therefore Several amperes can however be passed through a cathodic spot the surface of which is extremely small, this corresponding to densities of current which are tens of thousands of times greater than those indicated by Mr. Georges Claude in his aforementioned patent. But what is more surprising still, and essential is that, as applicant has discovered and contrary to the very general tendency in the manufacture of luminescent tubes themselves, these cathodic densities of current which are extremely high are suitable, as has been stated above, not only with the usual pressure of the order of millimeters, but even with such low pressures, as some tenths of a millimeter, for example, and even in certain cases'of a few hundredths of a millimeter that tubes operating under such low pressures on the luminescent principle would result in a very short life.

In applying these observations to an industrial purpose, applicant has produced a device for the production of light. This device which satisfies the objects of the present invention comprises an electric discharge apparatus intended to function on the arc principle and formed by a chamber enclosing the electrodes and a gaseous mass which contains at least one rare gas; this device is characterized by the feature that on the one hand the pressure of the gaseous mass in the chamber of the discharge apparatus has a value of between 3 millimeters and 0.05 millimeter of mercury, this pressure being lower, the greater the cross-section of the said chamber, and on the other hand the electric circuit connected to the electrodes of the chamber of the said apparatus has characteristics permitting the functioning of the discharge device on the arc principle,

Electric gaseous discharge apparatus for devices of the above kind can be made in various ways.

In one arrangement, the cathodic part of an apparatus of this kind is made according to my copending patent application filed October 22, 1931 for Electric gaseous discharge apparatus, Serial No. 570,450; metallic oxid cathodes for instance, incandescent cathodes can also be used as elements of such cathodic parts.

As regards the anode, applicant has found that it was possible to obtain industrial results which are particularly remarkable from the point of view of the life and good preservation with a discharge apparatus filled with low pressure gases by providing a special anode. This is again characteristic as up to now it seems that investigators have been mainly occupied with the problem of the cathode where the potential drop is very great on the luminescent principle. However since the cathodic drop is reduced to a. very low value, on changing from the luminescent principle to the arc principle the anodic drop is then of like importance. It has been much more diflicult to providev a good anode, since, as already'stated, only one small part of the anode surface is as a rule used.

Applicant has observed that the dimensions and the position of the anodic zone on the anode depend on the shape of the anode, its dimensions and its position in the apparatus and more particularly its position with regard to the walls of the apparatus. In the case, for example of a hollow cylindrical electrode the applicants have observed that the anodic zone is formed on the internal surface of the cylinder by a strip the depth of which is practically equal to twice the diameter of the cylinder and on the external surface of this by a strip, the depth of which increases with the distance of the electrode from the walls It has also been observed that all the surface elements of the anodic zone do not operate equally as the volatilization of the metal is more particulaly severe in the region of the intense electric field such as at the edges of the cylinder 7 and at any points or at parts of the surface which are acutely convex.

Finally it has been observed that the emission of particles of anodic material is particularly disadvantageous from the point of view of absorption of the gases when the particles projected can become deposited on parts which are cold or are insuiliciently heated and that theirfabsorbing property on the contrary diminishes very much if they are deposited on very hot regions, if for example the particles emitted from the points of the anode surface are deposited solely on the surface of the anode itself.

The various observations have led to the following arrangements which can be used singly or in various combinations:

1. The anode is arranged to have an anodic zone the surface of which has a minimum value determined by the pressure of the gaseous mass in the discharge apparatus. This value is preferably at least 1 square centimeter per ampere when this pressure is 3 millimeters of mercury and at least 8 square centimeters per ampere when this pressure is 0.05 millimeter and being of course located between those two limits when the value of the pressure lies between these two indi cated limits of pressure.

2. The total surface of the anode is at the maximum seven times greater than that of the anodic zone.

It must be noted how low these limiting values are with regard to that of 1.5 square decimeters per ampere indicated by Mr. Georges Claude in his patent mentioned above, and that they are conducive to anodes of reduced dimensions; such anodes can be very easily adapted to be utilized even for considerable current intensities.

3. The anode has a hollow form the depth of which in the electric field is at least equal to its diameter.

4. The parts of the anode susceptible to disintegration, that is to say the exterior surface or at the very least the part of this surface which can be emissive and also the edges of the anode, are coated with a suitable di-electric for example a film of silica, glass, quartz and the like. The protection of the edges can extend to a certain depth down the interior of the anode.

5. In order to reduce the intensity of the electric field due to charges on the walls of the apparatus, these walls and the anode are disposed at a sufiicient distance from each other that there is no deposition on these walls of volatilized ma terials from the anode. In these conditions deposition takes place on the internal surface of the anode and further when in use this internal surface has a temperature which is suiiicient for the gases not to be absorbed in a stable manner by this deposition.

Finally in another arrangement before putting the discharge apparatus into operation the interior walls and the electrodes of this apparatus are subject to the discharge action and to a pressure of the gaseous mass capable of determining at the end of a suiiiciently long time an occlusion of gas in the interior walls and the electrodes of the gaseous chamber. This occlusion can extend to the saturation of the elements. In this way, when the apparatus is functioning, and owing to an automatic action of regeneration, the absorption by volatilization cannot at any moment sensibly affeet the pressure and composition of the mixture of gases in the apparatus. The same result can also be obtained under the action of a temporary increase in the pressure alone. This gaseous ccclusion in the electrodes and in the walls or the apparatus has the advantage of considerably increasing the life of the discharge apparatus.

As soon asthe desired occlusion hasbeen obtained, the standard pressure is established in the gaseous chamber of the discharge apparatus, this latter being then ready to be put into operation.

The means which have been just described are also applicable to devices operating on alternating current, the cathode being at the neutral point and the anodes being equal in number to the number of phases. The use of three-phase current for example has the advantages of great facility in lighting and a great stability in operation. The light has a considerable stability by reason of the superposition of the three phases. In addition these three phase devices oifer very good equilibrium of phase for the distribution electric network.

By putting the above-mentioned means in operation it is easy to obtain apparatus which have a commercially long life without appreciable volatilization of the electrodes and without modifying thecolour of the light these advantages being particularly important in the case of mixtures of gases in spite of such low pressures which have been indicated and which are according to the requirements of the apparatus, between 3 mm and five hundredths of a millimeter of mercury.

It being thus possible to operate with low pressures on the arc principle, it is now expedient to insist on its industrial applications which as will be seen are of the greatest importance.

As a result of research, applicant has found in fact that it is precisely in the case of low pressures that the highest luminous efliciency is obtained from rare gases. Applicant has thus been able in certain cases to obtain an emciency which ismuch greater than those which have been obtained with tubes operating on the luminescent principle, these efliciencies even surpassing those of the gaseous incandescent lamps usually termed halfwatt lamps.

Furthermore the gradient of potential is generally also the smallest for these low pressures giving the maximum energy efliciency. The coincidence of the minimum voltage and the maximum emciency with reference to the pressure is more accurate the greater the transverse section of the gaseous'column so that for instance a large tube functioning on the arc principle will give the best efficiency when operating on a very low voltage or what is the same thing will have the greatest length at a given voltage. In addition, according as the pressure diminishes the quality of the light is sometimes modified in an advantageous manner, for example in the case of pure neon, the green and blue radiations are progressively intensified. The feed voltages can be again reduced and the stability increased by adding a very small portion of argon, krypton or xenon.

Thus by ignoring what seemed hitherto logical and the tendencies in the manufacture of luminescent tubes, and by utilizing the arc principle in combination with low pressures, applicant ob- {at one and the same time in any of the rare gaseous discharge tubes formed up to date, viz, great luminous intensities, possibility of feeding on low voltages, maximum length for a minimum voltage,

very high luminous efficiency never obtained up use.

The devices and apparatus oi the kind hereinabove described are properly new and included in the scope of the present invention together with arrangements including such devices and apparatus.

The application of the invention to apparatus operating electric discharges in a neon atmosphere and to installations comprising such devices will now be described byway of example without in any way restricting the ambit of the present invention.

In illumination installations using luminous neon tubes more particularly in decorative or luminous advertising installations constructed up to date, the main task has been to provide tubes having as long a life as possible whilst the luminous emciency of these installations has been of secondary consideration. In view of obtaining this long life, relatively high pressures have been usedin order to reduce the volatization of the electrodes. The art thus becomes much simpler but this simplicity is obtained to the great detriment. of the luminescent efliciency as will be shown below.

Applicant has observed in fact that with th relatively low pressures and working currents considered in the present application, the neon light tubes give a very high eiilciency thus rendering their application to the various uses which have just been indicated, possibleand even advantageous.

The drawings appended herewith show:

Fig. 1 curves relating to the functioning of the discharge devices according to the present invention.

Fig. 2 a diagram oi an electric lighting installation according to the present invention.

Fig. 1 shows three curves belonging to a set of curves experimentally obtained byapplicant. Each of these curves refers to an illuminating discharge device including an electric discharge tube in which the luminous column is formed by a tube of predetermined diameter d.

Each of these curves has been obtained by stating along abscissa (OK) the gaseous atmosphere pressures the tube'(in the present case neon) in millimeters of mercury and along ordinates (OY) the consumption of energy in watts per candle corresponding to the various pressures considered so that account may be taken of the variation in the specific consumption of the luminous column as a function of the pressure, the current intensity being constant.

These curves show that:

(a) For pressures between 1 mm. and 1% mm. of mercury the specific consumption limit that is to say the consumption in the positive column alone which ,is exclusive of the loss of energy at the electrodes,.is of the order of a half watt per candle and that it is substantially independent of the diameter of the tube.

(b) For higher pressures than 1 mm. the specific consumption increases when the pressure increases and the increase is greater the greater the diameter of the tube.

On the other hand for pressures lower than 1 millimeter the specific consumption decreases when the pressure becomes lower down to a minimum which is obtained for pressures graduating from 0.1 mm. to 1 mm. of mercury according to the diameter of the tube. The lowering of the specific consumption is more marked the greater the diameter of the tube.

(d) For each diameter of tube there is a pressure for which the specific consumption is a minimum.

For instance, the specific consumption, as shown by curve I representing a tube of 66 mm. diameter, is lowest at a pressure of .3 mm. of mercury, the specific consumption is lowest in the case of a tube of 36 mm. diameter (Curve II) when the pressure is at .6 mm. of mercury, and the specific consumption of a tube of 28 mm. diameter is lowest at a pressure of .7 mm. of mercury. From the foregoing, it will observed that the pressure of the gas in the tube is lower for a larger tube diameter and higher for a smaller tube diameter to obtain the lowest specific consumption. Thus, it may be stated that the pressure of the gas in the tube and the diameter of the tube bear an inverse relation to each other.

These curves made for neon gas are not peculiar only to this gas. Curves having similar characteristics could be given for other gaseous atmospheres.

The result of this is that it is possible to manufacture discharge tubes of the type described above and of a given diameter in which the gaseous atmosphere is at a pressure (lower than 1.5 mm.) corresponding to the minimum specific consumption for the said diameter or is of a pressure approximate to that corresponding this 0n the other hand the series of these curves make the existance of a zone A evident, this zone A being comprised between 1 mm. and 1% mm. for which the specific consumption is practically independent of the diameter of the tube.

From these results it is seen that it is desirable with tubes containing chiefly neon to use pressures which do not exceed 1 millimeter of mercury and the object of the present invention is to provide more especially discharge devices of the type described containing a gaseous atmosphere at a pressure not exceeding. 1 mm. of mercury.

But it may happen that a little luminous efficiency has to be sacrificed for other reasons. A discharge apparatus could therefore beused containing a gaseous atmosphere the pressure of which is lower or higher than that corresponding to the-minimum of specific consumption. For example with neon tubes of small diameters (lower than 30 mm.) the pressure which corresponds to the minimum specific consumption is indeed lower than the pressure under which the voltage necessary for feeding the tube is the lowest; in this case therefore, it is desirable to have a higher pressure than 1.5 millimeter but in any case the pressure should not exceed 3 millimeters of mercury for fear of affecting the luminous eiiiciency too much.

On the other hand it has been observed that in neon tubes having large diameters (more than mm.) the minimum voltage necessary for feeding is one corresponding to pressures which do not difier much from those which give the best luminous efliciency. For example it is quite remarkable that the minimum specific consumption of 0.3 watt per candle for a tube of 66 millimeters is obtained for a pressure of about 0.3 millimeter whilst for the same tube the pressure corresponding to the minimum feed voltage is 0.8 millimeter.

These various considerations show that it is also possible to construct discharge apparatus according to the invention in which the gaseous atmosphere has a pressure equal to that for which the feed voltage of the said apparatus is a minimum.

Results similar to the preceding ones have been obtained with gaseous atmospheres other than neon.

The present invention includes the said apparatus and devices comprising apparatus of this type.

Fig. 2-1 is a current generator for example a continuous current dynamo giving 110 volts connected through a lead 2 to the anode 3 of the discharge apparatus 4 and through a lead 5 to the cathode 6 of the said apparatus. '7 is a stabilization resistance calculated to absorb for example 10 per cent of the consumption of energy in the circuit. The voltage at the resistance terminals will therefore be about 10 volts and at the terminals of the discharge apparatus about 100 volts.

The discharge apparatus 4 is of the type described that is to say it contains a gaseous mass formed by. at least, a rare gas for example neon. The pressure of this gas is between 3 mm. and 0.5 mm. of mercury.

The electric circuit formed by the generator 1 the leads 2 and 3 and the discharge apparatus 4 is established in such a way that this discharge apparatus functions on the arc principle.

8 is an ignition arrangement of a suitable and known type producing the excess voltage necessary for putting the discharge apparatus into operation. This arrangement can be out 01f from the circuit when the discharge passes normally through the tube.

In the discharge apparatus 4, 9 is the luminous column. The anodic part 10 contains the anode 3 and the cathodic part 11 contains the cathode 6.

The cathode part 11 here conforms to that shown in Fig. 6 in my copending patent application filed October 22, 1931 for Electric gaseous discharge apparatus. Serial No. 570,450.

The anode 3 here has the form of a hollow cylinder closed at one of its ends. It is constructed so as to have an anodic zone 12, here shown between the lines 12' and 12" and the surface of which has a minimum value determined as described above. The total surface of this anode is at the most seven times greater than that of the surface of the anodic zone.

The part 13 of the exterior surface of the anode which can be emissive, as well as the edge 14 of the anode and the part 15 of the interior of the anode which is adjacent to this edge, are covered by a film 16 formed by a suitable di-electric.

The interior walls of the casing of the discharge apparatus are disposed around the anode at a suflicient distance to prevent the deposit of volatilized material on these walls and so that deposits can only be formed on the internal surface of the anode 3. In operation this internal surface is at a temperature sufiicient for the gases not to be absorbed in a stable manner by these deposits.

A screen 17 is preferably disposed in the cathodic part 11 in order to prevent the particles projected in a straight line i'rom the cathode from coming into the luminous column 9.

, Before putting the apparatus into use, its internal walls and its electrodes 3 and 6 have been charged with occluded gas as described above.

In the present application, it is to be understood that expression electric gaseous discharge apparatus means not only an electric gaseous discharge tube, but also any apparatus of the kind described provided with a discharge chamber of any other shape.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is:

1. A gaseous electric discharge device rorthe production of light comprising a spaced anode and cathode, a transparent envelope enclosing the electrodes and a gaseous atmosphere surrounding the electrodes, the gaseous atmosphere comprisingat least one rare gas maintained at a pressure between 0.05 and 3.0 millimeters of mercury, the pressure bearing an inverse relation to the cross-section of the envelope according to the formula d being the diameter of the section measured in centimeters, and an electrical circuit including a source or electrical energy and externally connecting the anode and cathode, said electrical circuit and the conditions in the envelope being so adjusted as to produce an arc discharge in said tube. Y

2.' A gaseous electric discharge device for the production of light comprising a spaced anode and cathode, a transparent envelope enclosing the electrodes and a gaseous atmosphere surrounding the electrodes, the gaseous atmosphere comprising at least one rare gas maintained at a pressure between 0.05 and 3.0 millimeters of mercury, the pressure bearing an inverse relation to the cross-section of the envelope according to the formula d being the diameter of the section measured in centimeters, and an electrical circuit including a source of electrical energy and externally connecting the anode and cathode, said electrical circuit and the conditions in the envelope being so adjusted as to produce an arc discharge in said envelope, the portion of said envelope surrounding the cathode being of greater cross-section than the rest of the envelope to maintain the wells of this portion of the envelope at a temperature lower than that of the other portions of the envelope to maintain volatilized cathodic material in the cathode chamber.

3. A gaseous electric discharge device for the production of light comprising a spaced anode and cathode, a transparent envelope enclosing the electrodes and a gaseous atmosphere surrounding the electrodes, the gaseous atmosphere comprising at least one rare gas maintained at a pressure between 0.05 and 3.0 millimeters of mercury, the pressure bearing an inverse relation to the cross-section of the envelope according to the formula it being the diameter of the section measured in centimeters, and an electrical circuit including a source of electrical energy and externally connecting the anode and cathode, said electrical circuit and the conditions in the envelope being so adjusted as to produce an arc discharge in said envelope, the portion of the envelope surrounding the cathode and constituting the cathode chamber being constructed to thermally and me chanically prevent the flow of cathodic material from the cathode chamber into the luminous part of the envelope.

4. A gaseous electric discharge device for the production of light comprising a spaced anode and cathode, a transparent envelope enclosing the electrodes and a gaseous atmosphere surrounding the electrodes, the gaseous atmosphere consisting of a rare gas maintained at a pressure between 0.05 and 3.0 millimeters of mercury, the pressure bearing an inverse relation to the crosssection of the envelope according to the formula 4 being the diameter of the section measured in centimeters, and an electricalcircuit including a source of electrical energy and externally conenvelope, and said cathode being of the metaloxide type.

5. A gaseous electric discharge device as set Iorth in claim 1, in which the anode of the discharge apparatus has an anodic zone. the surface of which has a minimum value determined by the pressure of the gaseous mass in the discharge apparatus, this value ranging between 1 square centimeter per ampere when this pressure is 3 millimeters of mercury and 8 square centimeters per ampere when the pressure is 0.05 millimeters.

6. A gaseous electric discharge device as set forth in claim 1, in which the anode of the discharge apparatus has an anodic zone, the area of which at the minimum is one-seventh'the total area of the anode.

'1. A gaseous electric discharge device as set forth in claim 1, in which the anode of the discharge apparatus is hollow, the depth of the hollow in the electric field set up in the discharge 9. A gaseous electric discharge device as set forth in claim 1, in which the anode of the discharge apparatus is set away from the interior walls of the discharge apparatus at a distance which is suflicient to prevent any deposition of volatilized material on these walls, the anode being so constructed that any deposit is confined to the interior face of said anode which is of a sumcient temperature to prevent the gases from being absorbed by this deposit.

10. A-gaseous electric discharge device as set forth in claim 1, in which the anodic elements, the cathode and the interior walls of the discharge apparatus are charged in any proportion up to saturation with occluded gases identical with those of the gas charge of the apparatus.

11. A gaseous electric discharge device as set forth in claim 1, in which the discharge apparatus includes a gaseous atmosphere containing neon equal in proportion at least to that which is necessary to keep the electric characteristics of this apparatus practically the same as those of an apparatus containing pure neon, this arrangement being characterized by the feature that the gaseous atmosphere of the discharge apparatus has a pressure which bears an inverse relation to the diameter of the luminous chamber of this apparatus and which is, for instance, of 1.2 millimeters of mercury for discharge tubes of 10 millimeters of diameter and 0.3 millimeter of mercury for discharge tubes of 60 millimeters of diameter.

12. A method of producing a gaseous electric discharge in a discharge apparatus containing a rare gas, comprising selecting a discharge tube having a determined cross-section, then selecting a gas pressure in the tube between 3.0 and 0.05 mm. mercury, and adjusting the pressure so that the pressure in terms of mm. of mercury bears an inverse relation to the cross-section of the tube in terms of mm. diameter according to the approximate proportion:

13. A method as set forth in claim 12, in which before putting the apparatus into operation the interior walls and the electrodes of the said apparatus are subject to a discharge action in such conditions of intensity of current and of pressure of the gaseous mass and for such length of time that an occlusion ofgas takes place in the interior walls and the electrodes of the gaseous chamber, this occlusion being extended in any proportion up to the saturation of the said elements.

14. A method as set forth in claim 12, in which the apparatus is preliminarily subjected to a discharge with the pressure increased above that at which the apparatus is to be operated to effect the occlusion of the gases in the interior walls and electrodes of the apparatus.

ANDRE CLAUDE. 

